Expression of GM-CSF receptors in male germ cells and their role in signaling for increased glucose and vitamin C transport

We studied the expression and function of the granulocyte‐macrophage colony stimulating factor (GM‐CSF) receptor in male germ cells. RT‐PCR showed expression of mRNAs encoding the α‐ and β‐subunits of the GM‐CSF receptor in human testis, and the presence of the α‐ and β‐proteins was confirmed by immunoblotting with anti‐α and anti‐β‐antibodies. Immunolocalization studies showed the level of expression of GM‐CSF α‐ and β‐subunits in the germ line in the testis and in ejaculated spermatozoa. Receptor binding studies using radiolabeled GM‐CSF revealed that bull spermatozoa have about 105 high‐affinity sites with a Kd of 222 pM and ≈1100 low‐affinity sites with a Kd of 10 nM. GM‐CSF signaled, in a time‐ and dose‐dependent manner, for an increased uptake of glucose and vitamin C. J. Cell. Biochem. 80:625–634, 2001. © 2001 Wiley‐Liss, Inc.